Kenwood KVT 719DVD + Navigation KNA-G510

Hello everyone. I just recently purchased a 2004 M3 in San Diego and would like to install a Kenwood flip up screen KVT719DVD and integrated Navigation KNA-G510. My car comes with the Harman Kardon sound system. I do not want to change the stock speakers and SUB that came with the unit. Any advice on removing the stock BMW CD that came with the car and installing this system? What good websites sell installation kits for the M3? Thanks

Check out Crutchfiled.com for a wiring harness. I have an aftermarket Kenwood unit in my '06 M3 - If your '04 is like my '06, make sure the kit you get has the RCA cables...I did the install myself, pretty easy, just be careful when removing the trim piece from around the factory radio - the plastic pins can break.